Motor-driven needle valve for refrigerating circuit and refrigerating device with the motor-driven needle valve

ABSTRACT

Formed in a valve main body ( 1 ) is a refrigerant flow path ( 41 ) for lowering the amount of flow of a refrigerant which flows into an internal space ( 30 ) of a casing ( 3 ) from a refrigerant flow path ( 9 ) through a needle fit/insert clearance ( 17 ) defined between a needle fit/insert aperture ( 16 ) and a needle ( 2 ) inserted into the needle fit/insert aperture ( 16 ). When, with the rise or drop in refrigerant pressure, refrigerant flows through the needle fit/insert clearance ( 17 ), adhesion of sludge included in the refrigerant to the wall surface of the needle fit/insert clearance ( 17 ) is reduced by a lessened amount of refrigerant flow in the needle fit/insert clearance ( 17 ) by the refrigerant flow path ( 41 ). This therefore prevents, as far as possible, malfunction of the needle ( 2 ) due to sludge adhesion, thereby ensuring proper operation of the needle ( 2 ).

TECHNICAL FIELD

The present invention relates to an electrically operated needle valveused for controlling the amount of flow of a refrigerant in arefrigerating circuit and to a refrigerating system provided with suchan electrically operated needle valve.

BACKGROUND ART

Referring to FIG. 14, there is shown a construction of an electricallyoperated expansion valve Z₀ which is used for controlling the amount offlow of a refrigerant in a refrigerating circuit. A concrete descriptionof the construction of the prior art electrically operated expansionvalve Z₀ will be made below for providing a description of the presentinvention which will be set forth later.

In FIG. 14, the electrically operated expansion valve Z₀ has a valvemain body 1, a needle 2, and a casing 3. The valve main body 1 is formedinto a different diameter body including a flow path formation portion 1a of larger diameter which is positioned on the side of one axial end ofthe valve main body 1, a screw thread formation portion 1 c of smallerdiameter which is positioned on the side of the other axial end of thevalve main body 1, and a shoulder portion 1 b of medium diameter whichis positioned between the flow path formation portion 1 a and the screwthread formation portion 1 c. The shoulder portion 1 b and the screwthread formation portion 1 c are inserted into an internal space 30 ofthe casing 3 through an opening 33 formed in one end face of the casing3. And, the valve main body 1 is made integral with the casing 3 withthe shoulder portion 1 b and the screw thread formation portion 1 cinserted in the casing 3.

The flow path formation portion 1 a of the valve main body 1 is providedwith a refrigerant flow path 9. The refrigerant flow path 9 is composedof a refrigerant introduction portion 11 and a refrigerant withdrawalportion 12, these portions 11 and 12 being approximately orthogonal toeach other. Formed at an opening edge of the refrigerant introductionportion 11 is a valve seat portion 15. A refrigerant introduction pipe13 is connected to the refrigerant introduction portion 11, whereas arefrigerant withdrawal pipe 14 is connected to the refrigerantwithdrawal portion 12.

A needle fit/insert aperture 16 having a given diameter is formed in thevalve main body 1. The needle fit/insert aperture 16 is so formed as toextend from the refrigerant flow path 9 of the flow path formationportion 1 a to an end of the screw thread formation portion 1 c. And,one end of the needle fit/insert aperture 16 opens to the refrigerantflow path 9, whereas the other end of the needle fit/insert aperture 16opens to an end face of the screw thread formation portion 1 c.

The needle 2 is slidably inserted into the needle fit/insert aperture16. Formed at one end of the needle 2 is a valve head portion 20. Theneedle 2 travels back and forth along its axial direction, therebyincreasing and decreasing the area of a passage between the valve headportion 20 and the valve seat portion 15. Because of such increase anddecrease in path area, the amount of flow of a refrigerant flowing fromthe refrigerant introduction pipe 13 to the refrigerant withdrawal pipe14 is controlled. Further, when the valve head portion 20 seats againstthe valve seat portion 15, the refrigerant flow path 9 is placed in thefully closed state. As a result, the circulation of the refrigerant isstopped.

The needle 2 is composed of a stepped shaft body including a slidingshaft portion 2 a of larger diameter which is positioned on the side ofthe valve head portion 20 and a supporting shaft portion 2 b of smallerdiameter. And, the sliding shaft portion 2 a is slidably supported bythe valve main body 1 and the axial center position of the needle 2 isheld. An extremely narrow needle fit/insertion clearance 17 is definedbetween the inner peripheral surface of the needle fit/insert aperture16 and the sliding shaft portion 2 a of the needle 2. Further, definedbetween the inner peripheral surface of the needle fit/insert aperture16 and the supporting shaft portion 2 b is an inner peripheral clearance22 which is of larger clearance size than that of the needle fit/insertclearance 17.

On the other hand, a pressure equalization aperture 18 having a givendiameter is formed in the shoulder portion 1 b of the valve main body 1so that the needle fit/insert aperture 16 passing through the axialcenter portion of the shoulder portion 1 b and the lower end of theinternal space 30 of the casing 3 communicate to each other. That is, byvirtue of the formation of the pressure equalization aperture 18 ofgiven diameter, the needle fit/insert clearance 17 and a first spaceportion 31 (which will be described later) communicate with each other.

Further, formed on the outer peripheral surface of the screw threadformation portion 1 c of the valve main body 1 is an external thread. Arotor portion 10 constituting a part of an electrically operated means Xis disposed on the diameterwise outside of the screw thread formationportion 1 c. The electrically operated means X axially drives the needle2 and is composed of a so-called stepping motor. The electricallyoperated means X has the rotor portion 10 and an electromagnet 5disposed on the outer peripheral side of the casing 3.

The rotor portion 10 has a screw thread formation member 7 and a spacer6. The screw thread formation member 7 is formed into a bottomedtubular-like shape. Formed on the inner peripheral surface of aperipheral wall portion 7 a of the screw thread formation member 7 is aninternal thread which meshes with the external thread of the screwthread formation portion 1 c of the valve main body 1. The spacer 6 isformed into a tubular-like shape having collars at both ends thereof. Apermanent magnet 4 is positioned on the outer peripheral side of thespacer 6. On the other hand, the peripheral wall portion 7 a of thescrew thread formation member 7 is force-fit in the inner peripheralside of the spacer 6 and fixed there rigidly.

The rotor portion 10 is inserted from above the screw thread formationportion 1 c of the valve main body 1 with the screw thread formationmember 7 engaging with the screw thread formation portion 1 c so thatthe rotor portion 10 is attached to the valve main body 1. Accordingly,the rotor portion 10 rotates in correspondence to the amount ofenergization (pulse value) of the electromagnetic 5 and makes a relativemovement in the axial direction of the screw thread formation portion 1c with respect to the screw thread formation portion 1 c of the valvemain body 1.

The needle 2 is connected to the rotor portion 10 so that the needle 2is placed in the opened or closed state by the axial movement of therotor 10. That is, the upper end of the needle 2 passes through an endface portion 7 b of the screw thread formation member 7 and projectstherefrom upwardly. The projecting end of the needle 2 is provided witha retaining member 34. The retaining member 34 prevents the needle 2from slipping downwardly from the screw thread formation member 7.Further, a compression spring 35 is positioned between a step portionbetween the sliding shaft portion 2 a and supporting shaft portion 2 bof the needle 2 and the lower surface of the end face portion 7 b of thescrew thread formation member 7. The spring 35 constantly appliespressing force to the needle 2 and to the screw thread formation member7 in the direction in which the retaining member 34 abuts against theend face portion 7 b of the screw thread formation member 7.

Accordingly, in the range up to the time that the valve head portion 20seats against the valve seat portion 15, the needle 2 travels with theaxial movement of the rotor portion 10 for the increase or decrease inpassage area. On the other hand, when the valve head portion 20 seatsagainst the valve seat portion 15, further downward movement of theneedle 2 is regulated. In this state, the rotor portion 10, whilecompressing the spring 35, downwardly travels just a given distance.And, the needle 2 is held in the closed valve state by energizing forceof the spring 35. In this case, there is defined a given clearancebetween the retaining member 34 and the end face portion 7 b of thescrew thread formation member 7 (for example, see FIGS. 9 and 10 aboutembodiments of the present invention).

In order to adequately hold a magnet effect between the permanent magnet4 and the electromagnet 5, the gap between the permanent magnet 4 andthe inner peripheral surface of the casing 3 should be set extremelysmall by the rotor portion 10. Such a gap is for example about 0.2 mm.Therefore, the internal space 30 of the casing 3 is zoned by the rotorportion 10 into a first space portion 31 defined below the rotor portion10 and a second space portion 32 defined above the rotor portion 10. Thefirst and second space portions 31 and 32 communicate to each otherthrough an outer peripheral clearance 21 defined between the outerperipheral surface of the permanent magnet 4 and the inner peripheralsurface of the casing 3.

The prior art electrically operated expansion valve Z₀ generally has theabove-described structure.

When there is a rise in refrigerant pressure on the upstream side of theelectrically operated expansion valve Z₀ by compressor drive, theelectrically operated expansion valve Z₀ receives such a refrigerantpressure rise. As a result, there is produced a pressure differential inthe inside of the electrically operated expansion valve Z₀.Consequently, a part of the refrigerant flows into the internal space 30of the casing 3 from the refrigerant flow path 9 through the needlefit/insert clearance 17.

That is, a part of the refrigerant flowing into the needle fit/insertclearance 17, after passing through the pressure equalization aperture18 in communication with the needle fit/insert clearance 17, directlyflows into the first space portion 31.

On the other hand, the remaining refrigerant flows upward through theneedle fit/insert clearance 17. Further, the remaining refrigerant flowsupward through the inner peripheral clearance 22 defined between aportion of the needle 2 located nearer to the other end thereof and theneedle fit/insert aperture 16 of the valve main body 1 from the needlefit/insert clearance 17. Thereafter, the refrigerant is reversed andflows downward through an engagement portion clearance 23 definedbetween the screw thread formation portion 1 c of the valve main body 1and the screw thread formation member 7. Then, the refrigerant finallyreaches to the first space portion 31.

These refrigerants, which have flowed into the first space portion 31from the foregoing different two routes and merged together there,further flow upward through the outer peripheral clearance 21 and flowinto the second space portion 32.

Such refrigerant flow into the first and second space portions 31 and 32of the casing 3 cancels a difference in pressure between both the axialsides of the rotor portion 10. This ensures smooth movement of the rotorportion 10. In this state, the needle 2 moves with the movement of therotor portion 10, whereby the amount of refrigerant flow is controlled.

On the other hand, when the compressor stops operating and refrigerantpressure on the upstream side of the electrically operated expansionvalve Z₀ decreases, a refrigerant in the internal space 30 of the casing3 follows a route opposite to the above and is flowed back to therefrigerant flow path 9.

PROBLEMS THAT THE INVENTION INTENDS TO SOLVE

Incidentally, the temperature of a compressor sliding portion used in arefrigerating system becomes high under severe operating conditions dueto metal contact. As a result, refrigerating machine oil and processingoil remaining in the circuit will undergo degradation, thereby givingrise to the generation of sludge of high viscosity. Besides, the sludgehas the property of being refrigerant-insoluble or being difficult to bedissolved into a refrigerant, resulting in the generation of sludgewhich has not been dissolved into a refrigerant and remained separatedtherefrom. Such sludge thus generated circulates through therefrigerating circuit, together with the refrigerant.

In this case, with the compressor operation start and stop, in theelectrically operated expansion valve Z₀ refrigerant flows between therefrigerant flow path 9 and the internal space 30. Besides, therefrigerant flows through narrow clearances, namely, the needlefit/insert clearance 17, the engagement portion clearance 23, and theouter peripheral clearance 21. Consequently, sludge is likely to adhereto each of these clearances 17, 23, and 21.

If sludge adheres to the needle fit/insert clearance 17 and accumulatestherein, this obstructs the movement of the needle 2, that is, theaction of controlling the amount of refrigerant flow. On the other hand,if sludge adheres to the engagement portion clearance 23 and outerperipheral clearance 21 and accumulates thereon, this obstructs theoperation of the rotor portion 10. Any of these cases results inundesirable incidents such as compressor abnormal liquid compression andcompressor overheating.

Bearing in mind these problems, the present invention was made.Accordingly, an object of the present invention is to propose anelectrically operated needle valve for a refrigerating circuit capableof preventing, as far as possible, the adhesion of sludge and arefrigerating system which is equipped with such an electricallyoperated needle valve.

DISCLOSURE OF THE INVENTION

The present invention employs the following concrete means with a viewto providing solutions to the above-described problems.

An electrically operated needle valve for a refrigerating circuitaccording to a first invention of the present application is composed ofa valve main body 1 including a needle fit/insert aperture 16 throughwhich a needle 2 is slidably arranged and a refrigerant flow path 9which is formed face to face with one end side of the needle fit/insertaperture 16 and whose flow path area is adjusted by the needle 2, and acasing 3 which is attached to the valve main body 1 with the other endside of the needle fit/insert aperture 16 positioned within an internalspace 30 thereof and which houses in the internal space 30 at least apart of an electrically operated means X for driving the needle 2. And,the refrigerating circuit electrically operated needle valve of thefirst invention is characterized in that the valve main body 1 isprovided with a refrigerant flow amount lowering means P for loweringthe amount of flow of a refrigerant flowing into the internal space 30from the refrigerant flow path 9 through a needle fit/insert clearance17 formed between the needle fit/insert aperture 16 and the needle 2inserted in the needle fit/insert aperture 16.

A second invention of the present application is characterized in thatin the refrigerating circuit electrically operated needle valveaccording to the first invention the refrigerant flow amount loweringmeans P is a refrigerant flow path 41 which is formed in the valve mainbody 1 so as to establish, not through the needle fit/insert aperture16, a communication between the refrigerant flow path 9 and the internalspace 30.

A third invention of the present application is characterized in that inthe refrigerating circuit electrically operated needle valve accordingto the first invention the needle fit/insert aperture 16 has a largerdiameter aperture portion 16A located nearer to the refrigerant flowpath 9 and a smaller diameter aperture portion 16B, located nearer tothe electrically operated means X, for slidably supporting the needle 2,a pressure equalization aperture 18 is formed in the larger diameteraperture portion 16A, the pressure equalization aperture 18 being incommunication, not through the smaller diameter aperture portion 16B,with the internal space 30, and the larger diameter aperture portion 16Aand the pressure equalization aperture 18 together constitute therefrigerant flow amount lowering means P.

A fourth invention of the present application is characterized in thatin the refrigerating circuit electrically operated needle valveaccording to the third invention the larger diameter aperture portion16A is provided with a needle guide member 42 which, while slidablesupporting the needle 2, allows refrigerant circulation in the axialdirection of the larger diameter aperture portion 16A.

A fifth invention of the present application is characterized in that inthe refrigerating circuit electrically operated needle valve accordingto the first invention the needle fit/insert aperture 16 has a firstsmaller diameter aperture portion 16C located nearer to the refrigerantflow path 9, a second smaller diameter aperture portion 16E locatednearer to the electrically operated means X, and a larger diameteraperture portion 16D located midway between the first smaller diameteraperture portion 16C and the second smaller diameter aperture portion16E and having a diameter greater than that of the first smallerdiameter aperture portion 16C and an axial length longer than that ofthe first smaller diameter aperture portion 16C, the needle 2 isslidably supported either by the second smaller diameter apertureportion 16E or by both of the first smaller diameter aperture portion16C and the second smaller diameter aperture portion 16E, and a pressureequalization aperture 18 is formed in the larger diameter apertureportion 16D, the pressure equalization aperture 18 being incommunication, not through the second small diameter aperture portion16E, with the internal space 30, and the larger diameter apertureportion 16D and the pressure equalization aperture 18 togetherconstitute the refrigerant flow amount lowering means P.

A sixth invention of the present application is characterized in that inthe refrigerating circuit, electrically operated needle valve accordingto the first invention the refrigerant flow amount lowering means P isimplemented by a groove 43 (44) formed either in the outer peripheralsurface of the needle 2 or in the inner peripheral surface of the needlefit/insert aperture 16.

A seventh invention of the present application is characterized in thatin the refrigerating circuit electrically operated needle valveaccording to the third or fourth invention the valve main body 1 has abase portion 1A including the refrigerant flow path 9 and a secondaryportion 1B which is a separated portion from the base portion 1A and thelarger diameter aperture portion 16A is formed in the base portion 1Aand the smaller diameter aperture portion 16B is formed in the secondaryportion 1B.

An eighth invention of the present application is characterized in thatin the refrigerating circuit electrically operated needle valveaccording to the fifth invention the valve main body 1 has a baseportion 1A including the refrigerant flow path 9 and a secondary portion1B which is a separated portion from the base portion 1A and the firstsmaller diameter aperture portion 16C and the larger diameter apertureportion 16D are formed in the base portion 1A whereas the second smallerdiameter aperture portion 16E is formed in the secondary portion 1B.

A ninth invention of the present application is characterized in that inthe refrigerating circuit electrically operated needle valve accordingto any one of the third to fifth inventions the pressure equalizationaperture 18 is a round aperture and has an inside diameter of not lessthan 1.2 mm.

A tenth invention of the present application is characterized in that inthe refrigerating circuit electrically operated needle valve accordingto the ninth invention a plurality of the pressure equalizationapertures 18 are formed around the needle fit/insert aperture 16.

An eleventh invention of the present application is characterized inthat in the refrigerating circuit electrically operated needle valveaccording to any one of the first to tenth inventions the clearancedistance of the needle fit/insert clearance 17 is so set as to be notless than 0.2 mm.

An electrically operated needle valve for a refrigerating circuitaccording to a twelfth invention of the present application is composedof a valve main body 1 including a needle fit/insert aperture 16 throughwhich a needle 2 is slidably arranged and a refrigerant flow path 9which is formed face to face with one end side of the needle fit/insertaperture 16 and whose flow path area is adjusted by the needle 2, and acasing 3 which is attached to the valve main body 1 with the other endside of the needle fit/insert aperture 16 positioned within an internalspace 30 thereof and which houses in the internal space 30 at least apart of an electrically operated means X for driving the needle 2,wherein the electrically operated means X is provided with a screwthread portion which engages on the axial outer side of the needlefit/insert aperture 16 and which extends in the axial direction of theneedle fit/insert aperture 16 and an engagement clearance 23 thereofcommunicates with the needle fit/insert aperture 16 on the side of theother end of the needle fit/insert aperture 16. And, the refrigeratingcircuit electrically operated needle valve of the twelfth invention ischaracterized in that a refrigerant flow amount lowering means Q forlowering the amount of flow of a refrigerant flowing into the engagementclearance 23 from the refrigerant flow path 9 through the needlefit/insert aperture 16 is provided.

A thirteenth invention of the present application is characterized inthat in the refrigerating circuit electrically operated needle valveaccording to the twelfth invention the refrigerant flow amount loweringmeans Q is a communicating aperture 45 which is formed fact to face withthe other end of the needle fit/insert aperture 16 in the electricallyoperated means X.

A fourteenth invention of the present application is characterized inthat in the refrigerating circuit electrically operated needle valveaccording to the twelfth invention the refrigerant flow amount loweringmeans Q is a refrigerant flow path 49 (50), formed in an end of theneedle 2 fit and inserted in the needle fit/insert aperture 16, forbringing the needle fit/insert aperture 16 and the internal space 30into communication with each other when the needle 2 makes, in its axialdirection, a relative displacement with respect to the electricallyoperated means X.

An electrically operated needle valve for a refrigerating circuitaccording to a fifteenth invention is composed of a valve main body 1including a needle fit/insert aperture 16 through which a needle 2 isslidably arranged and a refrigerant flow path 9 which is formed face toface with one end side of the needle fit/insert aperture 16 and whoseflow path area is adjusted by the needle 2, and a casing 3 which isattached to the valve main body 1 with the other end side of the needlefit/insert aperture 16 positioned within an internal space 30 thereofand which houses in the internal space 30 at least a part of anelectrically operated means X for driving the needle 2, wherein an outerperipheral clearance 21 is formed between the outer peripheral surfaceof the electrically operated means X and the inner peripheral surface ofthe casing 3. And, the refrigerating circuit electrically operatedneedle valve of the fifteenth invention is characterized in that arefrigerant flow amount lowering means R for lowering the amount of flowof a refrigerant flowing between a first space portion 31 of theinternal space 30 located on one side of the electrically operated meansX and a second space portion 32 of the internal space 30 located on theother side of the electrically operated means X through the outerperipheral clearance 21.

A sixteenth invention of the present application is characterized inthat in the refrigerating circuit electrically operated needle valveaccording to the fifteenth invention the refrigerant flow amountlowering means R is a refrigerant flow path 46 which is formed through aperipheral wall area of a permanent magnet 4 of the electricallyoperated means X so that the refrigerant flow path 46 extends in theaxial direction of the permanent magnet 4.

A seventeenth invention of the present application is characterized inthat in the refrigerating circuit electrically operated needle valveaccording to the fifteenth invention the refrigerant flow amountlowering means R is a refrigerant flow path 47 which is formed through aperipheral wall area of a spacer 6, located on the inner peripheral sideof a permanent magnet 4 of the electrically operated means X, forholding the permanent magnet 4 so that the refrigerant flow path 47extends in the axial direction of the permanent magnet 4.

An eighteenth invention of the present application is characterized inthat in the refrigerant circuit electrically operated needle valveaccording to the fifteenth invention the refrigerant flow amountlowering means R is a refrigerant flow path 48 which is formed at anabutting area between a permanent magnet 4 of the electrically operatedmeans X and a spacer 6, located on the inner peripheral side of thepermanent magnet 4, for holding the permanent magnet 4.

A nineteenth invention of the present application is characterized inthat a refrigerating circuit electrically operated needle valve of anyone of the first to eighteenth inventions is employed as an expansionvalve.

A twentieth invention of the present application is characterized inthat in the refrigerating system according to the nineteenth inventionan HFC refrigerant or mixed refrigerant containing HFC, both of therefrigerants being of higher theoretical discharge temperature than thatof R22, is used as the refrigerant.

A twenty-first invention of the present application is characterized inthat in the refrigerating system according to the nineteenth inventionan HFC refrigerant or mixed refrigerant containing HFC, both of therefrigerants being of higher theoretical discharge temperature than thatof R12 and R502, is used as the refrigerant.

A twenty-second invention of the present application is characterized inthat in the refrigerating system according to the nineteenth invention asingle refrigerant of R32 or mixed refrigerant containing R32 is used asthe refrigerant.

A twenty-third invention of the present application is characterized inthat in the refrigerating system according to the nineteenth invention asynthetic oil is used as a refrigerating machine oil.

A twenty-fourth invention of the present application is characterized inthat in the refrigerating system according to the twenty-secondinvention polyol ester, carbonic ester, polyvinyl ether, alkyne benzene,or polyalkylene glycol is used as a base oil of the synthetic oil.

A twenty-fifth invention of the present application is characterized inthat in the refrigerating system of the twentieth or twenty-firstinvention a synthetic oil containing an extreme pressure additive isused as a refrigerating machine oil.

A twenty-sixth invention of the present application is characterized inthat in the refrigerating system according to any one of the nineteenthto twenty-fifth inventions a plurality of utilization-side heatexchangers or heat source-side heat exchangers are provided.

EFFECTS OF THE INVENTION

The inventions of the present application provide the following effects.

The refrigerating circuit electrically operated needle valve accordingto the first invention includes a valve main body (1) having a needlefit/insert aperture (16) and a refrigerant flow path (9) to which oneend of the needle fit/insert aperture (16) opens, a casing (3) attachedto the valve main body (1), a needle (2), inserted in the needlefit/insert aperture (16), for adjusting the flow path area of therefrigerant flow path (9), and electrically operated means (X) fordriving the needle (2). Further, the valve main body (1) on the otherside of the needle fit/insert aperture (16) is positioned in an internalspace (30) of the casing (3), while at least a part of the electricallyoperated means (X) is housed in the internal space (30) of the casing(3). Additionally, the valve main body (1) is provided with refrigerantflow amount lowering means (P) for lowering the amount of flow of arefrigerant flowing into the internal space (30) from the refrigerantflow path (9) through a needle fit/insert clearance (17) formed betweenthe needle fit/insert aperture (16) and the needle (2).

Accordingly, when, with the rise or drop in refrigerant pressure on theupstream side of the electrically operated needle valve, a refrigerantflows through the needle fit/insert clearance 17, the amount ofrefrigerant flow in the needle fit/insert clearance 17 is lowered by therefrigerant flow amount lowering means P. By such a drop in refrigerantflow amount, the amount of adhesion of sludge included in therefrigerant to the wall surface of the needle fit/insert clearance 17 isreduced, thereby preventing, as far as possible, malfunction of theneedle 2 due to sludge adhesion. This ensures that the needle 2functions properly, and abnormal liquid compression or overheating inthe compressor of the refrigerating circuit is forestalled, thereforeachieving improved reliability.

In the refrigerating circuit electrically operated needle valveaccording to the second invention, the refrigerant flow amount loweringmeans (P) is a refrigerant flow path (41) which is formed in the valvemain body (1) so as to establish another communication between therefrigerant flow path (9) and the internal space (30) independently ofthe needle fit/insert aperture (16).

Accordingly, the refrigerant flows mostly through the refrigerant flowpath 41 of smaller path resistance, and the refrigerant flow amount ofthe needle fit/insert clearance 17 is reduced relatively, whereby, bysuch reduction, adhesion of sludge to the wall surface of the needlefit/insert clearance 17 can be suppressed. That is, the effect of thefirst invention can be accomplished without fail by a simple,inexpensive arrangement, i.e., by forming the refrigerant flow path 41.

In the refrigerating circuit electrically operated needle valve of thethird invention according to the first invention, the needle fit/insertaperture (16) comprises a larger diameter aperture portion (16A) locatednearer to the refrigerant flow path (9) and a smaller diameter apertureportion (16B), located nearer to the electrically operated means (X),for movably supporting the needle (2). Additionally, the refrigerantflow amount lowering means (P) is composed of a pressure equalizationaperture (18) which is formed in the valve main body (1) so as toestablish another communication between the larger diameter apertureportion (16A) and the internal space (30) independently of the smallerdiameter aperture portion (16B), and the larger diameter apertureportion (16A).

In accordance with the refrigerating circuit electrically operatedneedle valve of the third invention, a region, located nearer to therefrigerant flow path 9 and corresponding to the larger diameteraperture portion 16A, of the needle fit/insert clearance 17 definedbetween the inner peripheral surface of the needle fit/insert aperture16 and the outer peripheral surface of the needle 2, has a path areagreater than that of a region corresponding to the smaller diameteraperture portion 16B, so that the former region is smaller in pathresistance than that of the latter region, and in addition the pressureequalization aperture 18 is formed in the larger diameter apertureportion 16A.

As a result of such arrangement, the refrigerant from the refrigerantflow path 9 mostly flows into the internal space 30 from the regioncorresponding to the larger diameter aperture portion 16A through thepressure equalization aperture 18, and the amount of flow of arefrigerant flowing through the smaller diameter aperture portion 16B isreduced relatively. As a result, although a corresponding region of theneedle fit/insert clearance 17 to the smaller diameter aperture portion16B is a narrow clearance, the adhesion of sludge to the region isprevented as far as possible. That is, the effect of the first inventioncan be accomplished without fail by a simple, inexpensive arrangement,i.e., by forming the larger diameter aperture portion 16A and pressureequalization aperture 18.

In the refrigerating circuit electrically operated needle valve of thefourth invention according to the third invention, the larger diameteraperture portion (16A) is provided with a needle guide member (42)which, while movably supporting the needle (2), allows refrigerantcirculation in the axial direction of the larger diameter apertureportion (16A).

Accordingly, while ensuring refrigerant circulation through the needlefit/insert clearance 17, the axial center of the needle 2 is held moreassuredly by the needle guide member 42. As a result, the effect of thethird invention is further speeded up.

In the refrigerating circuit electrically operated needle valve of thefifth invention according to the first invention, the needle fit/insertaperture (16) includes a first smaller diameter aperture portion (16C)located nearer to the refrigerant flow path (9), a second smallerdiameter aperture portion (16E) located nearer to the electricallyoperated means (X), and a larger diameter aperture portion (16D) locatedbetween the first smaller diameter aperture portion (16C) and the secondsmaller diameter aperture portion (16E) and having a diameter greaterthan that of the first smaller diameter aperture portion (16C) and anaxial length longer than that of the first smaller diameter apertureportion (16C). Further, the needle fit/insert aperture (16) is formed soas to movably support the needle (2) either by the second smallerdiameter aperture portion (16E) or by both of the first smaller diameteraperture portion (16C) and the second smaller diameter aperture portion(16E). Additionally, the refrigerant flow amount lowering means (P)comprises a pressure equalization aperture (18) which is formed in valvemain body (1) so as to establish another communication between thelarger diameter aperture portion (16D) and the internal space (30)independently of the second smaller diameter aperture portion (16E), andthe larger diameter aperture portion (16D).

In accordance with the refrigerating circuit electrically operatedneedle valve of the fifth invention, a region, located nearer to therefrigerant flow path 9 and corresponding to the larger diameteraperture portion 16A, of the needle fit/insert clearance 17 definedbetween the inner peripheral surface of the needle fit/insert aperture16 and the outer peripheral surface of the needle 2 has a path areagreater than that of regions corresponding to the first and secondsmaller diameter aperture portions 16C and 16E, so that the formerregion is smaller in path resistance than the latter regions. And, owingto the formation of the pressure equalization aperture 18 in thecorresponding region to the larger diameter aperture portion 16A, therefrigerant flowing into the larger diameter aperture portion 16D fromthe refrigerant flow path 9 through the first smaller diameter apertureportion 16C flows into the internal space 30 from the larger diameteraperture portion 16D mostly through the pressure equalization aperture18. As a result, the amount of flow of a refrigerant flowing through thesecond smaller diameter aperture portion 16E is relatively reduced,thereby preventing, as far as possible, the adhesion of sludge to thesecond smaller diameter aperture portion 16E. Further, althoughrefrigerant flows through the first smaller diameter aperture portion16C, its length is shorter in comparison with that of the largerdiameter aperture portion 16D, so that the amount of sludge adhesion tosuch a portion is maintained small.

This introduces a synergistic effect which prevents, as far as possible,the operation of the needle 2 from being checked by adhered sludge,thereby ensuring that the needle 2 operates properly. Therefore theeffect of the first invention is accomplished without fail.

In the refrigerating circuit electrically operated needle valve of thesixth invention according to the first invention, the refrigerant flowamount lowering means (P) is composed of a groove (43, 44) formed eitherin the outer peripheral surface of the needle (2) or in the innerperipheral surface of the needle fit/insert aperture (16).

Accordingly, when refrigerant flows through the needle fit/insertclearance 17 defined between the outer peripheral surface of the needle2 and the inner peripheral surface of the needle fit/insert aperture 16,the refrigerant flows mostly through the groove 43 (44) of smaller pathresistance. The refrigerant flow amount in narrow portions other thanthe groove 43 (44) is relatively reduced, and the adhesion of sludgeonto the wall surface of the needle fit/insert clearance 17 issuppressed. That is, the effect of the first invention is achievedwithout fail by a simple, inexpensive arrangement, i.e., by forming thegroove 43 (44).

In the refrigerating circuit electrically operated needle valve of theseventh invention according to the third or fourth invention, the valvemain body (1) is composed of a base portion (1A) including therefrigerant flow path (9) and a secondary portion (1B) which is aseparated portion from the base portion (1A) whereas the larger diameteraperture portion (16A) is formed in the base portion (1A) and thesmaller diameter aperture portion (16B) is formed in the secondaryportion (1B).

In the refrigerating circuit electrically operated needle valve of theeighth invention according to the fifth invention, the valve main body(1) comprises a base portion (1A) including the refrigerant flow path(9) and a secondary portion (1B) which is a separated portion from thebase portion (1A) and the first smaller diameter aperture portion (16C)and the larger diameter aperture portion (16D) are formed in the baseportion (1A) whereas the second smaller diameter aperture portion (16E)is formed in the secondary portion (1B).

In accordance with the refrigerating circuit electrically operatedneedle valves of the seventh and eighth inventions, in addition to beingcapable of obtaining the effects of the third to fifth inventions, forexample the processing of each aperture portion is easier to carry outin comparison with forming the valve main body 1 in one piece, and it ispossible to expect that the cost of manufacturing an electricallyoperated expansion valve is lowered.

In the refrigerating circuit electrically operated needle valve of theninth invention according to any one of the third to fifth inventions,the pressure equalization aperture (18) is a round aperture and has aninside diameter of not less than 1.2 mm. Such arrangement ensures thatthe pressure equalization aperture 18 is nearly prevented from cloggingdue to sludge adhesion. As a result, the operation of pressureequalization by the pressure equalization aperture 18 is maintainedwell.

In the refrigerating circuit electrically operated needle valve of thetenth invention according to the ninth invention, a plurality of thepressure equalization apertures (18) are formed around the needlefit/insert aperture (16). Such arrangement further speeds up theoperation of pressure equalization on the side of the refrigeratingcircuit electrically operated needle valve and allows the electricallyoperated needle valve to quickly shift to proper operation.

In the refrigerating circuit electrically operated needle valve of theeleventh invention according to any one of the first to sixthinventions, the clearance distance of the needle fit/insert clearance(17) is so set as to be not less than 0.2 mm. Such arrangement, whilemaintaining the action of holding the axial center of the needle 2 bythe needle fit/insert aperture 16, makes it possible to effectivelyreduce the adhesion of sludge to the wall surface of the needlefit/insert clearance 17. This introduces a synergistic effect by whichthe needle 2 can be kept operating properly over a long period of time.

The refrigerating circuit electrically operated needle valve of thetwelfth invention is composed of a valve main body (1) having a needlefit/insert aperture (16) and a refrigerant flow path (9) to which oneend of the needle fit/insert aperture (16) opens, a casing (3) attachedto the valve main body (1), a needle (2), inserted in the needlefit/insert aperture (16), for adjusting the flow path area of therefrigerant flow path (9), and electrically operated means (X) fordriving the needle (2). Further, the valve main body (1) on the otherside of the needle fit/insert aperture (16) is positioned in an internalspace (30) of the casing (3), while at least a part of the electricallyoperated means (X) is housed in the internal space (30) of the casing(3). Further, the electrically operated means (X) is provided with ascrew thread portion which engages with the valve main body (1) outsidethe needle fit/insert aperture (16) and extends in the axial directionof the needle fit/insert aperture (16) and an engagement clearance (23)between the screw thread portion of the electrically operated means (X)and the valve main body (1) communicates with one end of the needlefit/insert aperture (16). Additionally, a refrigerant flow amountlowering means (Q) for lowering the amount of flow of a refrigerantflowing into the engagement clearance (23) from the refrigerant flowpath (9) through the needle fit/insert aperture (16) is provided.

Accordingly, when, with the rise or drop in refrigerant pressure on theupstream side of the electrically operated needle valve, refrigerantflows toward the engagement clearance 23 through the needle fit/insertclearance 17, the amount of flow of a refrigerant flowing into theengagement clearance 23 is lowered by the refrigerant flow amountlowering means Q. By such a drop in refrigerant flow amount, the amountof adhesion of sludge included in the refrigerant to the wall surface ofthe engagement clearance 23 is reduced, thereby preventing, as far aspossible, malfunction of the screw thread portion due to sludgeadhesion. This therefore ensures that the electrically operated means Xfunctions properly, and abnormal liquid compression or overheating inthe compressor of the refrigerating circuit is forestalled, thereforeachieving improved reliability.

In the refrigerating circuit electrically operated needle valve of thethirteenth invention according to the twelfth invention, the refrigerantflow amount lowering means (Q) is a communicating aperture (45) which isformed fact to face with the other end of the needle fit/insert aperture(16) in the electrically operated means (X). Accordingly, refrigerantflowing into the side of the other end of the needle fit/insert aperture16 through the needle fit/insert clearance 17 between the needlefit/insert aperture 16 and the needle 2 flows mostly through thecommunicating aperture 45 which is of smaller path resistance smallerthan that of the engagement clearance 23. As a result, there occurs arelative drop in refrigerant flow amount in the engagement clearance 23,thereby reducing the adhesion of sludge to the wall surface of theengagement clearance 23. That is, in accordance with the thirteenthinvention the effect of the twelfth invention can be achieved assuredlyby a simple, inexpensive structure, i.e., by forming the communicatingaperture 45.

In the refrigerating circuit electrically operated needle valve of thefourteenth invention according to the twelfth invention, the refrigerantflow amount lowering means (Q) is a refrigerant flow path (49, 50),formed in an end of the needle (2), for bringing the needle fit/insertaperture (16) and the internal space (30) into communication with eachother when the needle (2) makes, in its axial direction, a relativedisplacement with respect to the electrically operated means (X).

Accordingly, when the needle 2 makes, in its axial direction, a relativedisplacement with respect to the electrically operated means X, i.e.,when the needle 2 is placed in the valve closed state, refrigerantflowing into the side of the other end of the needle fit/insert aperture16 through the needle fit/insert clearance 17 between the needlefit/insert aperture 16 and the needle 2 flows mostly through therefrigerant flow path 49 (50) which is of smaller path resistance thanthat of the engagement clearance 23. As a result, there occurs arelative drop in refrigerant flow amount in the engagement clearance 23,thereby reducing the adhesion of sludge to the wall surface of theengagement clearance 23. That is, in accordance with the fourteenthinvention the effect of the twelfth invention can be achieved assuredlyby a simple, inexpensive structure, i.e., by forming the refrigerantflow path 49 (50).

The refrigerating circuit electrically operated needle valve of thefifteenth invention includes a valve main body (1) having a needlefit/insert aperture (16) and a refrigerant flow path (9) to which oneend of the needle fit/insert aperture (16) opens, a casing (3) attachedto the valve main body (1), a needle (2), inserted in the needlefit/insert aperture (16), for adjusting the flow path area of therefrigerant flow path (9), and an electrically operated means (X) fordriving the needle (2). Further, the valve main body (1) on the otherside of the needle fit/insert aperture (16) is positioned in an internalspace (30) of the casing (3), while at least a part of the electricallyoperated means (X) is housed in the internal space (30) of the casing(3). Furthermore, an outer peripheral clearance (21) is formed betweenthe outer peripheral surface of the electrically operated means (X) andthe inner peripheral surface of the casing (3). Additionally, arefrigerant flow amount lowering means (R) for lowering the amount offlow of a refrigerant flowing between a first space portion (31) of theinternal space (30) located on one side of the electrically operatedmeans (X) and a second space portion (32) of the internal space (30)located on the other side of the electrically operated means (X) throughthe outer peripheral clearance (21).

Accordingly, when, with the rise or drop in refrigerant pressure on theupstream side of the electrically operated needle valve, refrigerantflows between the first space portion 31 and the second space portion 32through the outer peripheral clearance 21, the amount of flow of arefrigerant flowing into the outer peripheral clearance 21 is lowered bythe refrigerant flow amount lowering means R. By such a drop inrefrigerant flow amount, the amount of adhesion of sludge included inthe refrigerant to the wall surface of the outer peripheral clearance 21is reduced, thereby preventing, as far as possible, malfunction of theelectrically operated means X due to sludge adhesion. This thereforeensures that the electrically operated means X functions properly, andabnormal liquid compression or overheating in the compressor of therefrigerating circuit is forestalled, therefore achieving improvedreliability.

In the refrigerating circuit electrically operated needle valve of thesixteenth invention according to the fifteenth invention, therefrigerant flow amount lowering means (R) is a refrigerant flow path(46) formed in a peripheral wall area of a permanent magnet (4) of theelectrically operated means (X).

Accordingly, refrigerant flowing between the first space portion 31 andthe second space portion 32 flows mostly through the refrigerant flowpath 46 which is of smaller path resistance than that of the outerperipheral clearance 21. As a result, there occurs a relative drop inrefrigerant flow amount in the outer peripheral clearance 21, therebyreducing the adhesion of sludge to the wall surface of the outerperipheral clearance 21. That is, in accordance with the sixteenthinvention the effect of the fifteenth invention can be achievedassuredly by a simple, inexpensive structure, i.e., by forming therefrigerant flow path 46.

In the refrigerating circuit electrically operated needle valve of theseventeenth invention according to the fifteenth invention, therefrigerant flow amount lowering means (R) is a refrigerant flow path(47) formed in a peripheral wall area of a spacer (6), located on theinner peripheral side of a permanent magnet (4) of the electricallyoperated means (X), for holding the permanent magnet (4).

Accordingly, refrigerant flowing between the first space portion 31 andthe second space portion 32 flows mostly through the refrigerant flowpath 47 which is of smaller path resistance than that of the outerperipheral clearance 21. As a result, there occurs a relative drop inrefrigerant flow amount in the outer peripheral clearance 21, therebyreducing the adhesion of sludge to the wall surface of the outerperipheral clearance 21. That is, in accordance with the sixteenthinvention the effect of the fifteenth invention can be achievedassuredly by a simple, inexpensive structure, i.e., by forming therefrigerant flow path 47.

In the refrigerating circuit electrically operated needle valve of theeighteenth invention according to the fifteenth invention, therefrigerant flow amount lowering means (R) is a refrigerant flow path(48) formed between a permanent magnet (4) of the electrically operatedmeans (X) and a spacer (6), located on the inner peripheral side of thepermanent magnet (4), for holding the permanent magnet (4).

Accordingly, refrigerant flowing between the first space portion 31 andthe second space portion 32 flows mostly through the refrigerant flowpath 48 which is of smaller path resistance than that of the outerperipheral clearance 21. As a result, there occurs a relative drop inrefrigerant flow amount in the outer peripheral clearance 21, therebyreducing the adhesion of sludge to the wall surface of the outerperipheral clearance 21. That is, in accordance with the sixteenthinvention the effect of the fifteenth invention can be achievedassuredly by a simple, inexpensive structure, i.e., by forming therefrigerant flow path 48.

The refrigerating system of the nineteenth invention employs, as anexpansion valve, a refrigerating circuit electrically operated needlevalve according to any one of the first to sixth and twelfth toeighteenth inventions.

Accordingly, the electrically operated needle valve has a structurecapable of not easily failing to operate properly due to sludgeadhesion. Even when the expansion valve is used in such a condition thatsludge is relatively likely to be produced, its operation is maintainedin a proper condition without malfunction due to sludge adhesion. As aresult, the refrigerating system is improved in operation reliability.

In the refrigerating system of the twentieth invention according to thenineteenth invention, an HFC refrigerant or mixed refrigerant containingHFC, both of the refrigerants being of higher theoretical dischargetemperature than that of R22, is used as the refrigerant.

In this case, sludge that is generated in the compressor has such acharacteristic that the amount of sludge yield increases as therefrigerant discharge temperature goes up. Because of this, if an HFCrefrigerant or a mixed refrigerant containing HFC, both of which beingof higher theoretical discharge temperature than that of R22, is used asa refrigerant, this results in the increase in sludge yield amountitself. Accordingly, malfunctions due to sludge adhesion are likely tooccur in the electrically operated valve.

However, even in such a case, the refrigerating system of this inventionemploys, as the electrically operated expansion valve, a refrigeratingcircuit electrically operated needle valve of any one of the first tosixth and twelfth to eighteenth inventions, therefore ensuring that theelectrically operated expansion valve operates properly and properoperation of the refrigerating system is realized, although therefrigerant used produces much sludge due to its characteristic of highsludge yield.

In the refrigerating system of the twenty-first invention according tothe nineteenth invention, either an HFC refrigerant or mixed refrigerantcontaining HFC which is of higher theoretical discharge temperature thanthat of R12 and R502 is used as the refrigerant.

In this case, sludge that is generated in the compressor has such acharacteristic that the amount of sludge yield increases as therefrigerant discharge temperature goes up. Because of this, if an HFCrefrigerant or a mixed refrigerant containing HFC, both of which beingof higher theoretical discharge temperature than that of R12 and R502,is used as a refrigerant, this results in the increase in sludge yieldamount itself. Accordingly, malfunctions due to sludge adhesion arelikely to occur in the electrically operated valve.

However, even in such a case, the refrigerating system of this inventionemploys, as the electrically operated expansion valve, a refrigeratingcircuit electrically operated needle valve of any one of the first tosixth and twelfth to eighteenth inventions, therefore ensuring that theelectrically operated expansion valve operates properly and properoperation of the refrigerating system is realized, although therefrigerant used produces much sludge due to its characteristic of highsludge yield.

In the refrigerating system of the twenty-second invention according tothe nineteenth invention, a single refrigerant of R32 or mixedrefrigerant containing R32 is used as the refrigerant.

In such a case, R32 has several advantages such as low global warmingpotential and high energy efficiency when used in refrigerating systemsbecause of its high theoretical COP, high heat transfer rate, and lowrefrigerant pressure loss, but on the other hand R32 has somedisadvantages such as high sludge yield because of its higher dischargetemperature in comparison with R22 or the like.

However, even when the refrigerating system of this invention uses, asits refrigerant, a single refrigerant of R32 or R32-containing mixedrefrigerant, it is possible to ensure proper operation of theelectrically operated expansion valve although such a refrigerantproduces much sludge, for a refrigerating circuit electrically operatedneedle valve according to any one of the first to sixth and twelfth toeighteenth inventions is used as the electrically operated expansionvalve. This makes it possible to provide refrigerating systems of highglobal warming prevention effect.

In the refrigerating system of the twenty-third invention according tothe nineteenth invention, a synthetic oil is used as a refrigeratingmachine oil. Further, in the refrigerating system according to thetwenty-fourth invention, polyol ester, carbonic ester, polyvinyl ether,alkyne benzene, or polyalkylene glycol is used as a base oil of thesynthetic oil.

In such a case, unlike, for example, mineral oil which is used as arefrigerating machine oil in an R22 refrigerating system, the aforesaidsynthetic oil is composed of molecules having a molecular weight ofnarrow range and a nearly single structure. Because of this, thesynthetic oil is susceptible to damage when undergoing chemical changesby the influence of moisture, air, impurities, or the like. Besides,such chemical damage results in the increase in sludge yield.Accordingly, in a refrigerating system employing such a synthetic oil asa refrigerating machine oil, the electrically operated expansion valveis likely to fail to operate properly by sludge adhesion.

However, even when the refrigerating system of this invention uses, asits refrigerating machine oil, a synthetic oil such as polyol ester, itis possible to ensure proper operation of the electrically operatedexpansion valve although such a refrigerating machine oil has a propertyof high sludge yield, for a refrigerating circuit electrically operatedneedle valve according to any one of the first to sixth and twelfth toeighteenth inventions is used as the electrically operated expansionvalve, thereby making it possible to provide a refrigerating system ofhigh operational reliability.

In the refrigerating system of the twenty-fifth invention according tothe twentieth or twenty-first invention, a synthetic oil containing anextreme pressure additive is used as a refrigerating machine oil.

Generally, HFC refrigerant is inferior in self lubricity to HCFCrefrigerant, which results in the requirement that an extreme pressureadditive be added to refrigerating machine oil. However, such an extremepressure additive reacts with iron at a high-temperature metallicsliding surface and changes to sludge. Because of this, when an HFCrefrigerant is used and in addition a synthetic oil, to which an extremepressure additive is added, is used as a refrigerating machine oil, theelectrically operated expansion valve is liable to fail to operateproperly due to sludge adhesion.

However, even when the refrigerating system of this invention uses, asits refrigerating machine oil, a synthetic oil containing an extremepressure additive, it is possible to ensure proper operation of theelectrically operated expansion valve although such a refrigeratingmachine oil has a property of high sludge yield, for a refrigeratingcircuit electrically operated needle valve according to any one of thefirst to sixth and twelfth to eighteenth inventions is used as theelectrically operated expansion valve, thereby making it possible toprovide a refrigerating system of high operational reliability.

The refrigerating system of the twenty-sixth invention according to anyone of the nineteenth to twenty-fifth inventions is provided with aplurality of utilization-side heat exchangers or heat source-side heatexchangers.

In such a refrigerating system including a plurality of heat exchangers,the length of refrigerant piping is longer than for example arefrigerating system having a structure in which utilization-side heatexchangers and heat source-side heat exchangers are connected togetheron a one-for-one basis. Therefore, moisture, air, and impurities arepresent in larger amounts in the piping, and the probability that sludgeis generated becomes higher because of the inclusion of such contaminantin the refrigerating circuit. Accordingly, in a refrigerating systemincluding a plurality of utilization- or heat source-side heatexchangers, the malfunction of an electrically operated expansion valveis likely to be a problem.

However, even in such a case, a refrigerating circuit electricallyoperated needle valve having a structure hardly susceptible to sludgeadhesion is used as an electrically operated expansion valve, as in therefrigerating system of any one of the nineteenth to twenty-fifthinventions, it is possible to provide a highly reliable refrigeratingsystem free from the malfunction of the electrically operated expansionvalve in spite of the structure including a plurality of heat exchangersand therefore having a lengthy piping length.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a major part cross-sectional view showing the structure of anelectrically operated expansion valve as a first embodiment of therefrigerating circuit electrically operated needle valve of the presentinvention.

FIG. 2 is a major part cross-sectional view showing the structure of anelectrically operated expansion valve as a second embodiment of therefrigerating circuit electrically operated needle valve of the presentinvention.

FIG. 3 is a major part cross-sectional view showing the structure of anelectrically operated expansion valve as a third embodiment of therefrigerating circuit electrically operated needle valve of the presentinvention.

FIG. 4 is an enlarged cross-sectional view taken along IV—IV of FIG. 3.

FIG. 5 is a major part cross-sectional view showing the structure of anelectrically operated expansion valve as a fourth embodiment of therefrigerating circuit electrically operated needle valve of the presentinvention.

FIG. 6 is a major part cross-sectional view showing the structure of anelectrically operated expansion valve as a fifth embodiment of therefrigerating circuit electrically operated needle valve of the presentinvention.

FIG. 7 is a major part cross-sectional view showing the structure of anelectrically operated expansion valve as a sixth embodiment of therefrigerating circuit electrically operated needle valve of the presentinvention.

FIG. 8 is a major part cross-sectional view showing the structure of anelectrically operated expansion valve as a seventh embodiment of therefrigerating circuit electrically operated needle valve of the presentinvention.

FIG. 9 is a major part cross-sectional view showing the structure of anelectrically operated expansion valve as an eighth embodiment of therefrigerating circuit electrically operated needle valve of the presentinvention.

FIG. 10 is a major part cross-sectional view showing the structure of anelectrically operated expansion valve as a ninth embodiment of therefrigerating circuit electrically operated needle valve of the presentinvention.

FIG. 11 is a major part cross-sectional view showing the structure of anelectrically operated expansion valve as a tenth embodiment of therefrigerating circuit electrically operated needle valve of the presentinvention.

FIG. 12 is a major part cross-sectional view showing the structure of anelectrically operated expansion valve as an eleventh embodiment of therefrigerating circuit electrically operated needle valve of the presentinvention.

FIG. 13 is a major part cross-sectional view showing the structure of anelectrically operated expansion valve as a twelfth embodiment of therefrigerating circuit electrically operated needle valve of the presentinvention.

FIG. 14 is a major part cross-sectional view showing the structure of aconventional, typical refrigerating circuit electrically operatedexpansion valve.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described more specificallybased on preferred embodiments thereof.

Each of electrically operated expansion valves Z₁-Z₁₂ as embodiments ofthe present invention is identical in basic structure with the prior artelectrically operated expansion valve Z₀ shown in FIG. 14. Accordingly,components of each of the electrically operated expansion valves Z₁-Z₁₂corresponding to those described with reference to FIG. 14 showing theelectrically operated expansion valve Z₀ have been assigned the samereference numerals. In each of the embodiments of the present invention,the description of those corresponding to the components of theelectrically operated expansion valve Z₀ of FIG. 14 is omitted and onlycomponents proper to each embodiment will be described in detail.

EMBODIMENT 1

Referring to FIG. 1, there is shown an electrically operated expansionvalve Z₁ of a first embodiment of the present invention. FIG. 1 shows avalve main body 1, a needle 2, a casing 3, a permanent magnet 4, anelectromagnet 5, a spacer 6, a screw thread formation member 7, and arotor portion 10 composed of the permanent magnet 4, the spacer 6, andthe screw thread formation member 7. The rotor portion 10 andelectromagnet 5 together constitute an electrically operated means X.

The electrically operated expansion valve Z₁ of the present embodimentis intended for preventing, as far as possible, sludge adhesion in thewall surface of a narrow needle fit/insert clearance 17 formed between aneedle fit/insert aperture 16 formed in the valve main body 1 and theneedle 2 which is fit-inserted into the needle fit/insert aperture 16.The electrically operated expansion valve Z₁ of the present embodimentis designed to control, as far as possible, the adhesion of sludge tothe wall surface of the needle fit/insert clearance 17 by reducing theamount of a refrigerant flowing through the needle fit/insert clearance17, when, with the rise or drop in refrigerant pressure on the side ofthe refrigerant flow path 9 accompanied with the operation start andstop of a compressor (not shown), refrigerant flows between therefrigerant flow path 9 and the internal space 30 of the casing 3.

As a concrete means for the above, the first and second inventions ofthe present application are applied to the electrically operatedexpansion valve Z₁ of the present embodiment, wherein an adequate numberof refrigerant flow paths 41 (refrigerant flow amount lowering means P),through which the refrigerant flow path 9 and the first space portion 31on the side of the casing 3 directly (not through the needle fit/insertclearance 17) communicate to each other, is formed in areas of the flowpath formation portion 1 a of the valve main body 1.

As a result of such arrangement, when refrigerant flows between therefrigerant flow path 9 and the internal space 30 by a pressuredifferential between the side of the refrigerant flow path 9 and theside of the internal space 30, the amount of refrigerant flowing throughthe needle fit/insert clearance 17 is relatively reduced. That is, atthe time when the compressor starts operating, refrigerant flows fromthe side of the refrigerant flow path 9 toward the internal space 30,whereas at the time when the compressor stops operating, refrigerantflows from the side of the internal space 30 toward the refrigerant flowpath 9. The path resistance between the needle fit/insert clearance 17and each refrigerant flow path 41, 41, . . . is very much smaller on theside of each refrigerant flow path 41, 41, . . . than on the side of theneedle fit/insert clearance 17. Therefore, most of the refrigerant flowsthrough the refrigerant flow paths 41, 41, . . . , so that the amount ofrefrigerant flowing through the needle fit/insert clearance 17 isrelatively reduced.

As a result, because of such a relative drop in the amount ofrefrigerant flowing through the needle fit/insert clearance 17, theamount of sludge adhesion to the wall surface of the needle fit/insertclearance 17 is reduced in proportional to the drop in the amount ofrefrigerant flowing through the needle fit/insert clearance 17 even whenemploying a refrigerant or refrigerating machine oil of high sludgeyield.

Accordingly, the problem that the operation of the needle 2 is checkeddue to the adhering of high-viscosity sludge to the wall surface of theneedle fit/insert clearance 17 is prevented as far as possible, therebyensuring that the needle 2 operates properly. As a result, for exampleabnormal liquid compression or overheating in the compressor isforestalled, and the operation reliability of a refrigerating systemhaving the electrically operated expansion valve Z₁ is enhanced.

Additionally, since the refrigerant flow path 41 has a large path area,there occurs little sludge adhesion thereto. Further, in the presentembodiment each refrigerant flow path 41, 41, . . . is able to functionalso as the pressure equalization aperture 18 in the electricallyoperated expansion valve Z₀ of conventional construction, and there isprovided no pressure equalization aperture 18.

EMBODIMENT 2

Referring now to FIG. 2, there is shown an electrically operatedexpansion valve Z₂ according to a second embodiment of the presentinvention. The electrically operated expansion valve Z₂ is anelectrically operated expansion valve to which the first, third, seven,ninth, and tenth inventions of the present application are applied. Likethe electrically operated expansion valve Z₁ of the first embodiment,the electrically operated expansion valve Z₂ has a structure designedfor preventing the needle 2 from failing to operate properly due tosludge adhesion to the wall surface of the needle fit/insert clearance17.

That is, the electrically operated expansion valve Z₂ of the presentembodiment is characterized by the following structures.

(1) The valve main body 1 is characterized in structure as follows.

In the first embodiment, the valve main body 1 employs an integralstructure of the flow path formation portion 1 a, the shoulder portion 1b, and the screw thread formation portion 1 c. On the other hand, in thepresent embodiment the valve main body 1 employs a combined structure ofa base portion 1A including only the flow path formation portion 1 a andthe shoulder portion 1 b and a secondary portion 1B formed of a screwthread formation member 8 corresponding to the screw thread formationportion 1 c.

(2) The needle fit/insert aperture 16, which is formed extending overthe base portion 1A and the secondary portion 1B, is characterized asfollows.

The needle fit/insert aperture 16 is composed of a larger diameteraperture portion 16A positioned on the side of the base portion 1A and asmaller diameter aperture portion 16B positioned on the side of thesecondary portion 1B. The diameter dimension of the smaller diameteraperture portion 16B is set to a value approximate to the outsidediameter of the needle 2 in order to slidably support the needle 2, andthe clearance between the smaller diameter aperture portion 16B and theouter peripheral surface of the needle 2 is the needle fit/insertclearance 17. On the other hand, the diameter dimension of the largerdiameter aperture portion 16A is set greater than that of the smallerdiameter aperture portion 16B, and the clearance between the largerdiameter aperture portion 16A and the outer peripheral surface of theneedle 2 is an annular clearance 24 which is of greater clearancedimension than that of the needle fit/insert clearance 17.

(3) A plurality of the pressure equalization apertures 18 forestablishing communication between the annular clearance 24 and thefirst space portion 31 are formed in the base portion 1A.

The electrically operated expansion valve Z₂ of the present embodimentemploys the above-described distinctive structures (1)-(3), whereby thefollowing operation effects can be obtained.

First, in the case that refrigerant flows between the refrigerant flowpath 9 and the internal space 30 by the difference in pressuretherebetween, the path resistance between the needle fit/insertclearance 17 on the side of the secondary portion 1B and the annularclearance 24 on the side of the base portion 1A is very much smaller inthe annular clearance 24 than in the needle fit/insert clearance 17.Further, the pressure equalization aperture 18 is formed face to facewith the annular clearance 24, so that for example when considering sucha case that refrigerant flows from the refrigerant flow path 9 to theinternal space 30, the refrigerant, which has flowed into the annularclearance 24 from the refrigerant flow path 9, flows directly into thefirst space portion 31 through the pressure equalization aperture 18from the annular clearance 24. Because of this, the refrigerant amountof the needle fit/insert clearance 17 of greater path resistance isrelatively reduced.

As a result, because of such a relative drop in the amount ofrefrigerant flowing through the needle fit/insert clearance 17, theamount of sludge adhesion to the wall surface of the needle fit/insertclearance 17 is reduced in proportional to the drop in the amount ofrefrigerant flowing through the needle fit/insert clearance 17 even whenemploying a refrigerant or refrigerating machine oil of high sludgeyield. Accordingly, the problem that the operation of the needle 2 ischecked due to the adhering of high-viscosity sludge to the wall surfaceof the needle fit/insert clearance 17 is prevented as far as possible,thereby ensuring that the needle 2 operates properly. Because of this,for example abnormal liquid compression or overheating in the compressoris forestalled, and the operation reliability of a refrigerating systemhaving the electrically operated expansion valve Z₂ is enhanced.

Further, in this case the needle 2 is supported by the smaller diameteraperture portion 16B of the needle fit/insert aperture 16 on the side ofthe screw thread formation member 8 forming the secondary portion 1B.Such arrangement ensures that the axial center of the needle 2 is heldassuredly, and the controlling of refrigerant flow amount is carried outby the needle 2 with high reliability.

Further, in the electrically operated expansion valve Z₂ of the presentembodiment the valve main body 1 is composed of the base portion 1Aincluding the refrigerant flow path 9 and the secondary portion 1B whichis a separated portion from the base portion 1A. Because of this, forexample in comparison with forming the valve main body 1 in one piece,the processing of each aperture portion is easier to carry out, and itis possible to expect that the cost of manufacturing the electricallyoperated expansion valve Z₂ is lowered.

Further, for example if the pressure equalization aperture 18 is formedof a round aperture and its inside diameter is so set as to be not lessthan 1.2 mm, this ensures that the pressure equalization aperture 18 isnearly prevented from clogging due to sludge adhesion. As a result, notonly the operation of pressure equalization by the pressure equalizationaperture 18 is maintained well, but also proper operation of theelectrically operated expansion valve Z₂ is ensured.

In the electrically operated expansion valve Z₂ of the presentembodiment, the annular clearance 24 and the pressure equalizationaperture 18 together constitute a refrigerant flow amount lowering meansP.

EMBODIMENT 3

Referring to FIG. 3, there is shown an electrically operated expansionvalve Z₃ according to a third embodiment of the present invention. Theelectrically operated expansion valve Z₃ is an electrically operatedexpansion valve to which the first, third, fourth, seventh, ninth, andtenth inventions of the present application are applied. Theelectrically operated expansion valve Z₃, which is a further developedtype of the electrically operated expansion valve Z₂ of the secondembodiment, has a needle guide member 42 (which will be described below)at an area of the annular clearance 24, in addition to the samestructure as the electrically operated expansion valve Z₂.

The needle guide member 42 has an inner periphery as a needle fit/insertaperture 42 a having an inside diameter dimension capable of slidablysupporting the needle 2 and, on the other hand, a plurality ofrefrigerant flow paths 42 b, 42 b, . . . are formed on the outerperipheral side of the needle fit/insert aperture 42 a.

In the electrically operated expansion valve Z₃ including the needleguide member 42, in addition to the same operation effect that theelectrically operated expansion valve Z₂ of the second embodimentprovides, the following operation effect can be obtained. In theelectrically operated expansion valve Z₃, the needle guide member 42 isprovided and the needle 2 is slidably supported by both the needle guidemember 42 and the smaller diameter aperture portion 16B on the side ofthe screw thread formation member 8. Such arrangement further ensuresthat the axial center of the needle 2 is held assuredly, and theoperation reliability of the electrically operated expansion valve Z₃ isenhanced to a further extent.

In the electrically operated expansion valve Z₃ of the presentembodiment, the annular clearance 24 and the pressure equalizationaperture 18 together constitute a refrigerant flow amount lowering meansP.

EMBODIMENT 4

Referring to FIG. 5, there is shown an electrically operated expansionvalve Z₄ according to a fourth embodiment of the present invention. Theelectrically operated expansion valve Z₄ is an electrically operatedexpansion valve to which the first, fifth, eighth, ninth, and tenthinventions of the present application are applied. The electricallyoperated expansion valve Z₄ is a variation of the electrically operatedexpansion valve Z₃ according to the third embodiment. The electricallyoperated expansion valve Z₃ of the third embodiment is provide with theneedle guide member 42 by which the lower side of the needle 2 issupported. On the other hand, in the electrically operated expansionvalve Z₄ of the present embodiment it is arranged such that the lowerside of the needle 2 is supported on the side of the base portion 1,thereby eliminating the need for attachment of the needle guide member42.

That is, in the electrically operated expansion valve Z₄, the needlefit/insert aperture 16, which is so formed as to extend from the baseportion 1A to the secondary portion 1B, is composed of a first smallerdiameter aperture portion 16C which is positioned nearer to therefrigerant flow path 9 and which is of slightly greater diameterdimension than that of the outside diameter of the needle 2, a largerdiameter aperture portion 16D which is of greater diameter than that ofthe first smaller diameter aperture portion 16C, which is continuous tothe first smaller diameter aperture portion 16C, and to which one end ofthe pressure equalization aperture 18 opens, and a second smallerdiameter aperture portion 16E which is positioned on the side of thescrew thread formation member 8 forming the secondary portion 1B andwhich has approximately the same diameter dimension as that of the firstsmaller diameter aperture portion 16C. Further, in such a case the axiallength of the first smaller diameter aperture portion 16C is so set asto be shorter than that of the larger diameter aperture portion 16D.And, the needle 2 is supported by both the first smaller diameteraperture portion 16C and the second smaller diameter aperture portion16B.

As a result of employing such arrangement, it is possible to obtain thesame operation effect that the electrically operated expansion valve Z₃of the third embodiment achieves, without the provision of the needleguide member 42 of the electrically operated expansion valve Z₃ of thethird embodiment. In addition to this, it can be expected that theelimination of the need for the provision of the needle guide member 42lowers manufacture costs.

That is, in the electrically operated expansion valve Z₄ the annularclearance 24 corresponding to the larger diameter aperture portion 16Dis greater in path area and smaller in path resistance than the needlefit/insert clearance 25 formed in the first smaller diameter apertureportion 16C and the needle fit/insert clearance 17 corresponding to thesecond smaller diameter aperture portion 16E. Besides, because of theformation of the pressure equalization aperture 18 in an area of theannular clearance 24, the refrigerant, which flows to the largerdiameter aperture portion 16D from the refrigerant flow path 9 throughthe smaller diameter aperture portion 16C, flows toward the internalspace 30 mostly from the larger diameter aperture portion 16D of smallpath resistance through the pressure equalization aperture 18. Becauseof this, the amount of flow of a refrigerant flowing through the needlefit/insert clearance 17 is reduced relatively.

As a result, it is possible to control, as far as possible, sludgeadhesion in the needle fit/insert clearance 17. Further, refrigerantflows also in the corresponding area of the needle fit/insert clearance25 to the first smaller diameter aperture portion 16C. However, sincethe length of such an area is shorter than that of the larger diameteraperture portion 16D, the amount of sludge adhesion to the area issmall. This introduces a synergistic effect which prevents, as far aspossible, the operation of the needle 2 from being checked and, as aresult, proper operation of the needle 2 is ensured.

In the electrically operated expansion valve Z₄ of the presentembodiment, the annular clearance 24 and the pressure equalizationaperture 18 together constitute a refrigerant flow amount lowering meansP.

EMBODIMENTS 5 AND 6

FIG. 6 shows an electrically operated expansion valve Z₅ according to afifth embodiment of the present invention. FIG. 7 shows an electricallyoperated expansion valve Z₆ according to a sixth embodiment of thepresent invention. Each of these electrically operated expansion valvesZ₅ and Z₆ of the fifth and sixth embodiments is an electrically operatedexpansion valve to which the first and sixth inventions of the presentapplication are applied. Like the electrically operated expansion valvesZ₁-Z₄ of the foregoing embodiments, the electrically operated expansionvalves Z₅ and Z₆ are designed for preventing sludge adhesion in areas ofthe needle fit/insert clearance 17, but they differs from theelectrically operated expansion valves Z₁-Z₄ in concrete structure foraccomplishing such sludge adhesion prevention.

That is, the electrically operated expansion valves Z₅ and Z₆ of thefifth and sixth embodiments are based on the structure of the prior artelectrically operated expansion valve Z₀ of FIG. 14. In addition, in theelectrically operated expansion valve Z₅ of the fifth embodiment aspirally extending groove 43 is formed in the outer peripheral surfaceof the sliding shaft portion 2 a of the needle 2. On the other hand, inthe electrically operated expansion valve Z₆ of the sixth embodiment aplurality of grooves 44, 44, . . . extending in the axial direction ofthe needle 2 are f formed.

In accordance with these structures, refrigerant flowing between therefrigerant flow path 9 and the internal space 30 passes through theneedle fit/insert clearance 17. In such a case, either the groove 43 orgroove 44 is formed in the outer peripheral surface of the needle 2facing the e needle fit/insert clearance 17, so that in the needlefit/insert clearance 17 an area facing the groove 43 or 44 is greater inpath area than the other areas.

Because of this, refrigerant flowing through the needle fit/insertclearance 17 flows mostly through the area of larger path areacorresponding to each groove 43 and 44, and the amount of refrigerantflow in an area other than the area corresponding to each groove 43 and44 is relatively reduced. And, in the area corresponding to each groove43 and 44 its path area is large and there occurs little sludge adhesionthereto. Further, also in the areas other than the area corresponding toeach groove 43, and 44 the amount of refrigerant flowing therethrough issmall, so that even when its clearance is narrow sludge adhesion theretois maintained extremely small.

As a result, even when employing a refrigerant or refrigerating machineoil of high sludge yield, sludge adhesion in a narrow clearance area ofthe needle fit/insert clearance 17 is prevented as far as possible,thereby ensuring proper operation of the needle 2. Because of this, forexample abnormal liquid compression or overheating in the compressor isforestalled, and the operation reliability of a refrigerating systemhaving the electrically operated expansion valve Z₅ or Z₆ is enhanced.

In the electrically operated expansion valve Z₅ of the fifth embodiment,the groove 43 corresponds to the refrigerant flow amount lowering meansP. On the other hand, in the electrically operated expansion valve Z₆ ofthe sixth embodiment, the groove 44 corresponds to the refrigerant flowamount lowering means P.

Further, the grooves 43 and 44 are not limited to the above arrangementin which they are formed in the outer peripheral surface of the needle 2as in the fifth and sixth embodiments. For example the grooves 43 and 44may of course be formed in the inner peripheral surface of the needlefit/insert aperture 16 of the valve main body 1 and alternatively theyare formed both in the outer peripheral surface of the needle 2 and inthe inner peripheral surface of the needle fit/insert aperture 16.

EMBODIMENT 7

Referring to FIG. 8, there is shown an electrically operated expansionvalve Z₇ according to a seventh embodiment of the present application.The electrically operated expansion valve Z₇ of the present embodimentis an electrically operated expansion valve to which the twelfth andthirteenth inventions of the present application are applied. Theelectrically operated expansion valve Z₇ is intended for preventingsludge adhesion in the engagement clearance 23 when refrigerant flowsthrough the engagement clearance 23 between the screw thread formationportion 1 c of the valve main body 1 and the screw thread formationmember 7. To this end, the electrically operated expansion valve Z₇ ofthe present embodiment is equipped with a refrigerant flow amountlowering means Q for lowering the amount of flow of a refrigerantflowing through the engagement clearance 23.

This seventh embodiment and eighth and ninth embodiments which will bedescribed later are embodiments specifying their respective concretestructures of the refrigerant flow amount lowering means Q.

The electrically operated expansion valve Z₇ of the seventh embodimentis intended for lowering the amount of a refrigerant flowing toward theengagement clearance 23 of the whole refrigerant which flows out towardthe end face of the screw thread formation portion 1 c of the valve mainbody 1 from the refrigerant flow path 9 through the needle fit/insertclearance 17. To this end, a plurality of communicating apertures 45,45, . . . are formed in the end face portion 7 b of the screw threadformation member 7 which is arranged so as to cover the end face side ofthe screw thread formation portion 1 c of the valve main body 1.

And, refrigerant flowing into the end face portion 7 b by way of theneedle fit/insert clearance 17 is passed through each communicatingaperture 45, 45, . . . so that the refrigerant flows out directly to thesecond space portion 32. The electrically operated expansion valve Z₇ isSO formed as to relatively lower the amount of flow of a refrigerantflowing into the engagement clearance 23 by the communicating apertures45, 45, and so on. In the electrically operated expansion valve Z₇ ofthe present embodiment, the communicating aperture 45 corresponds to therefrigerant flow amount lowering means Q.

As described above, even when employing a refrigerant or refrigeratingmachine oil of high sludge yield, sludge adhesion is prevented as far aspossible because in the narrow engagement clearance 23 the amount offlow of a refrigerant flowing therethrough itself is made small bylowering the amount of flow of a refrigerant passing through theengagement clearance 23. This ensures not only proper operation of therotor portion 10 (rotational movement and axial movement) but alsoproper operation of the electrically operated expansion valve Z₇, andabnormal liquid compression or overheating in the compressor isforestalled in a refrigerating system with the electrically operatedexpansion valve Z₇. High operation reliability is obtained.

EMBODIMENTS 8 AND 9

FIG. 9 shows an electrically operated expansion valve Z₈ according to aneighth embodiment of the present application. On the other hand, FIG. 10shows an electrically operated expansion valve Z₉ according to a ninthembodiment of the present application. Each of the electrically operatedexpansion valves Z₈ and Z₉ of these embodiments is an electricallyoperated expansion valve to which the twelfth and fourteenth inventionsof the present application are applied. Like the electrically operatedexpansion valves Z₇ of the seventh embodiment, these electricallyoperated expansion valves Z₈ and Z₉ are intended for preventing sludgeadhesion in the engagement clearance 23, but they differs from theelectrically operated expansion valve Z₇ in concrete structure (i.e., instructure of the refrigerant flow amount lowering means Q) foraccomplishing such sludge adhesion prevention.

That is, the electrically operated expansion valves Z₈ and Z₉ of theseembodiments each make utilization of a given clearance created betweenthe fastening member 34 and the end face portion 7 b of the screw threadformation member 7 when the needle 2 is in its fully closed state. Moreconcretely, as shown in FIGS. 9 and 10, when the valve head portion 20of the needle 2 seats against the valve seat portion 15 of therefrigerant flow path 9, further downward movement of the needle 2 isregulated.

In this state, pressing force is applied, in a specified direction inwhich the valve is placed in the closed state, to the needle 2, as aresult of which the rotor portion 10 makes further downward movementagainst energizing force by the spring 35 and relatively displaces withrespect to the needle 2. At that time, there is created a givenclearance between the fastening member 34 formed at an end of thesupporting shaft portion 2 b of the needle 2 and the end face portion 7b of the screw thread formation member 7, and the end of the supportingshaft portion 2 b of the needle 2 projects into the second space portion32. By making utilization of this, a refrigerant flow path 49 (50) isformed in the outer peripheral surface of the needle 2 located nearer tothe end of the supporting shaft portion 2 b of the needle 2. In theelectrically operated expansion valve Z₈ of the eighth embodiment, therefrigerant flow path 49 is composed of a plurality of longitudinalgrooves. In the electrically operated expansion valve Z₉ of the ninthembodiment, the refrigerant flow path 50 is composed of a plurality ofspiral grooves.

In such an arrangement, the upper end side of the needle fit/insertclearance 17 (i.e., the communicating side to the engagement clearance23) is brought into direct communication with the second space portion32 through the refrigerant flow path 49 (50) when the needle 2 is in itsfully closed state. Because of this, most of the refrigerant flowingupward through the needle fit/insert clearance 17 directly flows out tothe second space portion 32 by way of the refrigerant flow path 49 (50)of small path resistance. Accordingly, the amount of refrigerant flow inthe engagement clearance 23 is relatively reduced.

As a result, as in the electrically operated expansion valve Z₇ of theseventh embodiment, even when employing a refrigerant or refrigeratingmachine oil of high sludge yield, sludge adhesion in the area of thenarrow engagement clearance 23 is prevented as far as possible. Thisensures not only proper operation of the rotor portion 10 (rotationalmovement and axial movement) but also proper operation of theelectrically operated expansion valves Z₈ and Z₉, and in a refrigeratingsystem with the electrically operated expansion valve Z₈ or Z₉ abnormalliquid compression or overheating in the compressor is forestalled. Highoperation reliability is obtained.

In the electrically operated expansion valve Z₈ of the eighthembodiment, the refrigerant flow path 49 corresponds to the refrigerantflow amount lowering means Q. On the other hand, in the electricallyoperated expansion valve Z₉ of the ninth embodiment the refrigerant flowpath 50 corresponds to the refrigerant flow amount lowering means Q.

EMBODIMENTS 10-12

FIGS. 11-13 show an electrically operated expansion valve Z₁₀ accordingto a tenth embodiment of the present application, an electricallyoperated expansion valve Z₁₁ according to an eleventh embodiment of thepresent application, and an electrically operated expansion valve Z₁₂according to a twelfth embodiment of the present application,respectively.

Each of the electrically operated expansion valves Z₁₀-Z₁₂ of theseembodiments is an electrically operated expansion valve to which thefifteenth to eighteenth inventions of the present application areapplied. Each of the electrically operated expansion valves Z₁₀-Z₁₂ isintended for preventing sludge adhesion in the narrow outer peripheralclearance 21 formed between the outer peripheral wall of the casing 3and the outer peripheral surface of the permanent magnet 4 positioned inthe outermost periphery of the rotor portion 10 and placed face to facewith the outer peripheral wall of the casing 3. To this end, eachelectrically operated expansion valve Z₁₀-Z₁₂ is provided with arefrigerant flow amount lowering means R for lowering the amount of flowof the refrigerant in the outer peripheral clearance 21.

First, in the electrically operated expansion valve Z₁₀ shown in FIG. 11according to the tenth embodiment, refrigerant flow paths 46, 46, . . .are formed in areas of the peripheral wall of the permanent magnet 4,penetrating therethrough in the axial direction. The first and secondspace portions 31 and 32 are brought into communication with each otherby each refrigerant flow path 46, 46, . . .

Further, in the electrically operated expansion valve Z₁₁ shown in FIG.12 according to the eleventh embodiment, refrigerant flow paths 47, 47,. . . are formed in areas of the peripheral wall of the spacer 6 tightlyclasping therein the permanent magnet 4, penetrating therethrough in theaxial direction. The first and second space portions 31 and 32 arebrought into communication with each other by each refrigerant flow path47, 47, . . .

Furthermore, in the electrically operated expansion valve Z₁₂ shown inFIG. 13 according to the twelfth embodiment, refrigerant flow paths 48,48, . . . are formed in areas of the abutting surface of the permanentmagnet 4 and the spacer 6 tightly clasping therein the permanent magnet4, penetrating therethrough in the axial direction. The first and secondspace portions 31 and 32 are brought into communication with each otherby each refrigerant flow path 48, 48, . . . In this case, therefrigerant flow path 48 is not limited to one that is formed in theouter peripheral surface of the spacer 6 as in the twelfth embodiment.For example, the refrigerant flow path 48 may be formed in an innerperipheral surface area of the permanent magnet 4 or may be formed bothin the permanent magnet 4 and in the spacer 6.

As a result of such arrangement, when there is a flow of refrigerantfrom the first space portion 31 to the second space portion 32 by apressure differential between the refrigerant flow path 9 and theinternal space 30, the path resistance between the outer peripheralclearance 21 and the refrigerant flow path (46, 47, 48) is smaller onthe side of the latter (the refrigerant flow path (46, 47, 48)) than onthe side of the former (the outer peripheral clearance (21)).Accordingly, most of the refrigerant flows through the refrigerant flowpath (46, 47, 48), and the amount of refrigerant flowing through theouter peripheral clearance 21 is relatively reduced by an amount ofrefrigerant flowing through the refrigerant flow path (46, 47, 48).

As a result, because of such a relative drop in the amount ofrefrigerant flowing through the outer peripheral clearance 21, theamount of sludge adhesion to the wall surface of the outer peripheralclearance 21 (i.e., the amount of sludge adhesion to the innerperipheral surface of the casing 3 and to the outer peripheral surfaceof the permanent magnet 4) decreases by an amount corresponding to sucha refrigerant flow amount drop, even when employing a refrigerant orrefrigerating machine oil of high sludge yield. Accordingly, the problemthat the operation of the rotor portion 10 is checked due to adhesion ofsludge in the outer peripheral clearance 21 is prevented as far aspossible, thereby ensuring proper operation of the needle 2. As aresult, for example abnormal liquid compression or overheating in thecompressor is forestalled, and the operation reliability of arefrigerating system having the electrically operated expansion valveZ₁₀, Z₁₁, or Z₁₂ is enhanced.

In the tenth to twelfth embodiments, the refrigerant flow paths 46, 47,and 48 each correspond to a refrigerant flow amount lowering means R.

OTHER EMBODIMENTS

The electrically operated expansion valves Z₁-Z₁₂ of the foregoingembodiments show concrete examples for individually preventing sludgeadhesion in different narrow clearances where there is a fear thatsludge adhesion occurs. That is, the electrically operated expansionvalves Z₁-Z₁₂ of the foregoing embodiments individually prevent sludgeadhesion in the needle fit/insert clearance 17, in the outer peripheralclearance 21, and in the engagement clearance 23.

However, from the viewpoint of ensuring that inconveniences due tosludge adhesion are prevented more assuredly in the entire electricallyoperated expansion valve, the present invention may be a complexstructure of an adequate combination of the structures shown in theelectrically operated expansion valves Z₁-Z₁₂ of the foregoingembodiments.

INDUSTRIAL APPLICABILITY

As described above, the present invention provides an electricallyoperated expansion valve for a refrigerating circuit and a refrigeratingsystem including such an electrically operated expansion valve usefulfor controlling the amount of flow of a refrigerant. The presentinvention is particularly suitable for cases in which HFC refrigerant orthe like is used.

What is claimed is:
 1. An electrically operated needle valve for arefrigerating circuit, comprising a valve main body (1) having a needlefit/insert aperture (16) and a refrigerant flow path (9) to which oneend of said needle fit/insert aperture (16) opens, a casing (3) attachedto said valve main body (1), a needle (2), inserted in said needlefit/insert aperture (16), for adjusting the flow path area of saidrefrigerant flow path (9), and for zoning said refrigerant flow path (9)into a refrigerant introduction portion (11) and a refrigerantwithdrawal portion (12), and electrically operated means (X) for drivingsaid needle (2), wherein said valve main body (1) on the other side ofsaid needle fit/insert aperture (16) is positioned in an internal space(30) of said casing (3), while at least a part of said electricallyoperated means (X) is housed in said internal space (30) of said casing(3); and wherein said valve main body (1) is provided with refrigerantflow amount lowering means (P) that allows a refrigerant to followbetween said refrigerant introduction portion (11) of said refrigerantflow path (9) and said internal space (30) in two opposite directionswithout flowing through a needle fit/insert clearance (17), so as tolower the amount of flow of a refrigerant flowing into said internalspace (30) from said refrigerant flow path (9) through said needlefit/insert clearance (17) formed between said needle fit/insert aperture(16) and said needle (2).
 2. The refrigerating circuit electricallyoperated needle valve of claim 1, wherein said refrigerant flow amountlowering means (P) is a refrigerant flow path (41) which is formed insaid valve main body (1) so as to establish another communicationbetween said refrigerant flow path (9) and said internal space (30)independently of said needle fit/insert aperture (16).
 3. Anelectrically operated needle valve for a refrigerating circuit,comprising a valve main body (1) having a needle fit/insert aperture(16) and a refrigerant flow path (9) to which one end of said needlefit/insert aperture (16) opens, a casing (3) attached to said valve mainbody (1), a needle (2), inserted in said needle fit/insert aperture(16), for adjusting the flow path area of said refrigerant flow path(9), and electrically operated means (X) for driving said needle (2),wherein said valve main body (1) on the other side of said needlefit/insert aperture (16) is positioned in an internal space (30) of saidcasing (3), while at least a part of said electrically operated means(X) is housed in said internal space (30) of said casing (3); whereinsaid valve main body (1) is provided with refrigerant flow amountlowering means (P) for lowering the amount of flow of a refrigerantflowing into said internal space (30) from said refrigerant flow path(9) through a needle fit/insert clearance (17) formed between saidneedle fit/insert aperture (16) and said needle (2); wherein said needlefit/insert aperture (16) comprises a larger diameter aperture portion(16A) located nearer to said refrigerant flow path (9) and a smallerdiameter aperture portion (16B), located nearer to said electricallyoperated means (X), for movably supporting said needle (2); and whereinsaid refrigerant flow amount lowering means (P) comprises a pressureequalization aperture (18) which is formed in said valve main body (1)so as to establish another communication between said larger diameteraperture portion (16A) and said internal space (30) independently ofsaid smaller diameter aperture portion (16B), and said larger diameteraperture portion (16A).
 4. The refrigerating circuit electricallyoperated needle valve of claim 3, wherein said larger diameter apertureportion (16A) is provided with a needle guide member (42) which, whilemovably supporting said needle (2), allows refrigerant circulation inthe axial direction of said larger diameter aperture portion (16A). 5.The refrigerating circuit electrically operated needle valve of claim 3or claim 4, wherein said valve main body (1) comprises a base portion(1A) including said refrigerant flow path (9) and a secondary portion(1B) which is a separated portion from said base portion (1A); andwherein said larger diameter aperture portion (16A) is formed in saidbase portion (1A) and said smaller diameter aperture portion (16B) isformed in said secondary portion (1B).
 6. An electrically operatedneedle valve for a refrigerating circuit, comprising, a valve main body(1) having a needle fit/insert aperture (16) and a refrigerant flow path(9) to which one end of said needle fit/insert aperture (16) opens, acasing (3) attached to said valve main body (1), a needle (2), insertedin said needle fit/insert aperture (16), for adjusting the flow patharea of said refrigerant flow path (9), and electrically operated means(X) for driving said needle (2), wherein said valve main body (1) on theother side of said needle fit/insert aperture (16) is positioned in aninternal space (30) of said casing (3), while at least a part of saidelectrically operated means (X) is housed in said internal space (30) ofsaid casing (3); wherein said valve main body (1) is provided withrefrigerant flow amount lowering means (P) for lowering the amount offlow of a refrigerant flowing into said internal space (30) from saidrefrigerant flow path (9) through a needle fit/insert clearance (17)formed between said needle fit/insert aperture (16) and said needle (2);wherein said needle fit/insert aperture (16) comprises a first smallerdiameter aperture portion (16C) located nearer to said refrigerant flowpath (9), a second smaller diameter aperture portion (16E) locatednearer to said electrically operated means (X), and a larger diameteraperture portion (16D) located between said first smaller diameteraperture portion (16C) and said second smaller diameter aperture portion(16E) and having a diameter greater than that of said first smallerdiameter aperture portion (16C) and an axial length longer than that ofsaid first smaller diameter aperture portion (16C); wherein said needlefit/insert aperture (16) is formed so as to movably support said needle(2) either by said second smaller diameter aperture portion (16E) or byboth of said first smaller diameter aperture portion (16C) and saidsecond smaller diameter aperture portion (16E); and wherein saidrefrigerant flow amount lowering means (P) comprises a pressureequalization aperture (18) which is formed in said valve main body (1)so as to establish another communication between said larger diameteraperture portion (16D) and said internal space (30) independently ofsaid second smaller diameter aperture portion (16E), and said largerdiameter aperture portion (16D).
 7. The refrigerating circuitelectrically operated needle valve of claim 6, wherein said valve mainbody (1) comprises a base portion (1A) including said refrigerant flowpath (9) and a secondary portion (1B) which is a separated portion fromsaid base portion (1A); and wherein said first smaller diameter apertureportion (16C) and said larger diameter aperture portion (16D) are formedin said base portion (1A) and said second smaller diameter apertureportion (16E) is formed in said secondary portion (1B).
 8. Therefrigerating circuit electrically operated needle valve of any one ofclaims 3-6, wherein said pressure equalization aperture (18) is a roundaperture and has an inside diameter of not less than 1.2 mm.
 9. Therefrigerating circuit electrically operated needle valve of claim 8,wherein a plurality of said pressure equalization apertures (18) areformed around said needle fit/insert aperture (16).
 10. An electricallyoperated needle valve for a refrigerating circuit, comprising a valvemain body (1) having a needle fit/insert aperture (16) and a refrigerantflow path (9) to which one end of said needle fit/insert aperture (16)opens, a casing (3) attached to said valve main body (1), a needle (2),inserted in said needle fit/insert aperture (16), for adjusting the flowpath area of said refrigerant flow path (9), and electrically operatedmeans (X) for driving said needle (2), wherein said valve main body (1)on the other side of said needle fit/insert aperture (16) is positionedin an internal space (30) of said casing (3), while at least a part ofsaid electrically operated means (X) is housed in said internal space(30) of said casing (3); wherein said valve main body (1) is providedwith refrigerant flow amount lowering means (P) for lowering the amountof flow of a refrigerant flowing into said internal space (30) from saidrefrigerant flow path (9) through a needle fit/insert clearance (17)formed between said needle fit/insert aperture (16) and said needle (2);wherein said refrigerant flow amount lowering means (P) comprises agroove (43, 44) formed either in the outer peripheral surface of saidneedle (2) or in the inner peripheral surface of said needle fit/insertaperture (16).
 11. The refrigerating circuit electrically operatedneedle valve of any one of claims 1-10, wherein the clearance distanceof said needle fit/insert clearance (17) is so set as to be not lessthan 0.2 mm.
 12. An electrically operated needle valve for arefrigerating circuit, comprising a valve main body (1) having a needlefit/insert aperture (16) and a refrigerant flow path (9) to which oneend of said needle fit/insert aperture (16) opens, a casing (3) attachedto said valve main body (1), a needle (2), inserted in said needlefit/insert aperture (16), for adjusting the flow path area of saidrefrigerant flow path (9), and electrically operated means (X) fordriving said needle (2), wherein said valve main body (1) on the otherside of said needle fit/insert aperture (16) is positioned in aninternal space (30) of said casing (3), while at least a part of saidelectrically operated means (X) is housed in said internal space (30) ofsaid casing (3); wherein said electrically operated means (X) isprovided with a screw thread portion which engages with said valve mainbody (1) outside said needle fit/insert aperture (16) and extends in theaxial direction of said needle fit/insert aperture (16); wherein anengagement clearance (23) between said screw thread portion of saidelectrically operated means (X) and said valve main body (1)communicates with one end of said needle fit/insert aperture (16); andwherein refrigerant flow amount lowering means (Q) for lowering theamount of flow of a refrigerant flowing into said engagement clearance(23) from said refrigerant flow path (9) through said needle fit/insertaperture (16) is provided.
 13. The refrigerating circuit electricallyoperated needle valve of claim 12, wherein said refrigerant flow amountlowering means (Q) is a communicating aperture (45) which is formed faceto face with the other end of said needle fit/insert aperture (16) insaid electrically operated means (X).
 14. The refrigerating circuitelectrically operated needle valve of claim 12, wherein said refrigerantflow amount lowering means (Q) is a refrigerant flow path (49, 50),formed in an end of said needle (2), for bringing said needle fit/insertaperture (16) and said internal space (30) into communication with eachother when said needle (2) makes, in its axial direction, a relativedisplacement with respect to said electrically operated means (X). 15.An electrically operated needle valve for a refrigerating circuit,comprising a valve main body (1) having a needle fit/insert aperture(16) and a refrigerant flow path (9) to which one end of said needlefit/insert aperture (16) opens, a casing (3) attached to said valve mainbody (1), a needle (2), inserted in said needle fit/insert aperture(16), for adjusting the flow path area of said refrigerant flow path(9), and electrically operated means (X) for driving said needle (2),wherein said valve main body (1) on the other side of said needlefit/insert aperture (16) is positioned in an internal space (30) of saidcasing (3), while at least a part of said electrically operated means(X) is housed in said internal space (30) of said casing (3); wherein anouter peripheral clearance (21) is formed between the outer peripheralsurface of said electrically operated means (X) and the inner peripheralsurface of said casing (3); and wherein refrigerant flow amount loweringmeans (R) for lowering the amount of flow of a refrigerant flowingbetween a first space portion (31) of said internal space (30) locatedon one side of said electrically operated means (X) and a second spaceportion (32) of said internal space (30) located on the other side ofsaid electrically operated means (X) through said outer peripheralclearance (21).
 16. The refrigerating circuit electrically operatedneedle valve of claim 15, wherein said refrigerant flow amount loweringmeans (R) is a refrigerant flow path (46) formed in a peripheral wallarea of a permanent magnet (4) of said electrically operated means (1).17. The refrigerating circuit electrically operated needle valve ofclaim 15, wherein said refrigerant flow amount lowering means (R) is arefrigerant flow path (47) formed in a peripheral wall area of a spacer(6), located on the inner peripheral side of a permanent magnet (4) ofsaid electrically operated means (X), for holding said permanent magnet(4).
 18. The refrigerating circuit electrically operated needle valve ofclaim 15, wherein said refrigerant flow amount lowering means (R) is arefrigerant flow path (48) formed between a permanent magnet (4) of saidelectrically operated means (X) and a spacer (6), located on the innerperipheral side of said permanent magnet (4), for holding said permanentmagnet (4).
 19. A refrigerating system employing a refrigerating circuitelectrically operated needle valve of any one of claims 1, 12 and 15 asan expansion valve.
 20. The refrigerating system of claim 19, wherein anHFC refrigerant or mixed refrigerant containing HFC, both of saidrefrigerants being of higher theoretical discharge temperature than thatof R32, is used as said refrigerant.
 21. The refrigerating system ofclaim 19, wherein an HFC refrigerant or mixed refrigerant containingHFC, both of said refrigerants being of higher theoretical dischargetemperature than that of R12 and R502, is used as said refrigerant. 22.The refrigerating system of claim 19, wherein a single refrigerant ofR32 or mixed refrigerant containing R32 is used as said refrigerant. 23.The refrigerating system of claim 19, wherein a synthetic oil is used asa refrigerating machine oil.
 24. The refrigerating system of claim 22,wherein polyol ester, carbonic ester, polyvinyl ether, alkyne benzene,or polyalkylene glycol is used as a base oil of said synthetic oil. 25.The refrigerating system of claim 20 or claim 18, wherein a syntheticoil containing an extreme pressure additive is used as a refrigeratingmachine oil.
 26. The refrigerating system of claim 19, wherein aplurality of utilization-side heat exchangers or heat source-side heatexchangers are provided.